Loop receiver



. April 9,1935. E, ZEP ER 1,997,221

LOOP RECEIVER File'd Oct. 24, 1933 g AMQl/F/EB I i Alla/Hm A INVENTOR ENCH ZEPLEPa v ATTORNEY v Patented Apr. 9, 1 935 7 .iFQLOQP QEiVER c Erich Zepler, Berlin; Germany, assignor to Tele -j funken Gesellschaft fiir; Drahtlose .{Ielegraphie- .l H., a corporationofGermany; I plicetienocteber 24,'19s3;-serie 1;N 694,937 In'Germany:Janua1fy22;193 "2claims;{ 01,1259520)" arrangementsadapted for use in the reception plane." 1

.of broadcast signals and the like; The invention Moresp ecifically;the presentinvention utilizes i's-parti'cularly concerned with-an arrangement a pair of crossed loops arranged preferably at i c. The present invention r iatesto ioop receiver tional receiving characteristics in the horizontal 5; of coils or loop's for receiving'signals emanating right angles-to each other and means for chang- V from ever dire'ctionwith substantiallyequal eming the phase of d ir d ien s p l 45 ciency irrespective of the position of the loops with degrees in each 0 1 s thatjthe Signalsliri respectto space. l w v common circuit are QOdegrees' out of phase with A particular object'ofthe invention is to devise; each other. s, of C ,D V y blICIKiI-Igv 101 an eflicient-system adapted for receiving signals out-action of desired signals since it is a well on movingvehicles whereby the're'ception' em-s known fact that fo ene y o b completely ciency is not afiectednby the directionof motion. b 01117115119 Phase difietellce mllfit be 180 ofthe vehicle. s I greesat the'point where the bucking action takes Loop antennae have th x p t of r e i g place;. The desired phase-:which is, in accordance G substantially'only signalsuemanatingfrom' transwit th 'in hti ,*o a n by Slightly tuh mitting' stations whose magnetic vector is orien- 'ingleach f theioop's at W l more tatedatright angles tor -the loopantenna, aipro'p' f ll i T erty extensively utilized :in direction; finders. Intheflifahling, Figure'ilirepl'esents'gfinemlly Howevenmsome instances loop iantennaarrangeg a circuitdiagram Hti iZBdIt XD iII h P in- 0- mentsareldesired which preferably have no spe p e nv cific selective. characteristics as is the case :in ure? represents diagrammatically .a more V automobile itype receivers. In. these instances. complete form:o'f the-invention utilizingcrossed horizontally mounted receiver loops are 'desirlocpsiinconnec i n i h bridge ir u t; able for general broadcast reception. LSuch hori- ;Figure-3 illustrates a-preierred embodimentof zontally i disposed. receiving antenna: insure no the-invention wherein-t-the crossed-loops feed into 25:

particularly favorable reception especially in View a (10111019 electronic tube Circuitof the circumstance that most long wave transn Fi '1, L1 and L2 arethe crossed receiver mitter equipments send out waves wh mag- -loops; As is obvious from said figure the oscillanetic vector is positioned horizontally. tions p k d p by i loops 'fe y w y of By using vertically orientated receiving loops phase s tin m s P connected i th l ads 3 the directional effects are obtained to a considerfrom th 1001) 1 a joint input circuit T able extent so that it has been'found desirable system-in Fi e 1 s ws y a sin phas to utilize two crossedloops having separate cirs t o p f in the d d t s: t cuits and combining the energy from the two may b desired, h to utilize two ha l p in any suitable reproducing system In this shifting devices so that the phase shift in each 35 system will not have to be large. The input circuit E is the usual input circuit connected with a thertnionictube, the output of which includes any suitable reproducing device R. From Figure 1 it will be-seen that the difierence in phase of 40 be bucked out unless special precautions be taken 25 z ifig i gi gfigfi g gg mi gg g fig 3:; i with the result that signals would not be. remen circuit p I V 'ceived from t d irections' 1 a InFig. 2 the twocrossed loops Liand L2 are The present mventwn contemplatesthe 'use'of provided with a tuning condenser C1 and C2 ree 45 two vertically orientated receiving loops or coils spectively 100p L1 is n cted to two opfor reception of signalling energy whose planes t points of a bridgemade up of condensers V are disposed at right angles to each other.- Broad- 1 ,0 c d, whil theioop L2 is connected 1y Speaking in the present invention, the ato opposite points of said bridge as shown. One

way fairly good reception is obtained from all directions. However, it is a fact'that even in such systems utilizing the crossed loops there exist the drawback that where the signal is equal in both loops theenergy from both the loops would 010118 Picked p y the tWO ivi 100DSare fed arm of the bridge, including the condenser C7, 5

byway of phase shifting means insuring a'lagforms "the input; circuit of an amplifier tube T1;-

ging of the currentsby an angle of 90 degrees the output of which is connected to the tuned to a joint or common utilizing circuit. It can input'l' of a second tube T2. The tuned input readily be shown that such an arrangement does circuit I includes a tuning condenser C which is not exhibit any pronounced selective or direcarranged for uni-control together with the tuning 55 2., r. 7 V I 1,997,271.

slightly detuned; one above the desired'fr'equency and the other below the desired frequency by the tuning condensers C1 and C2. Both loops feed into the single tube T1 through the bridge arrangement which arrangement prevents the tuning of one of the loops from eifecting the tuning of the other loop in well known manner;

7 In Figure 3, loop L1 and its associated tuning condenser C1, feeds into the inputof a tube T2 while the tube L2 with its associated-tuning-condenser C2 is arranged to form part of the input circuit of the tube T4. The outputs of vtubes :T3 and T4 are arranged push-pull fashion' and include the split transformer Z'coupled to the input 3 of amplifier tube T. The input 3 includes a tuning condenser C which is arranged for unicontrol together with the condensers C1 and C2. The output of the tubeZ is arranged tobe coupled in any suitable fashion to a detector circuit and the output of thedetector circuit may be passed through a suitable amplifier arrangement and reproducer device. 7 g j In operation of the system shown in Figure 3,

circuit 3 is tuned to the desired carrier by means" of the condenser C; Loop L1 is tuned slightly below the desired carrier by means of condenser C1 ,andloop L2 is tuned slightly above the carrier by means of the tuningfcondenser C2.- The tun-- ing of the 'loopsLrand L2 is arranged so that the phase difference of the Voltage. applied to the grids" of tubes T1 and T2 is approximately .90 degrees thereby preventing any bucking out action in the output of the tubes T3 and T4. It should be particularly noted that in the system shown'in Figure 3 interferin'g'frequencies produce similar phase inputs to the grids of tubes T3 and T4 so that the'interference tendsto cancel out in the difierential transformer 2, esp ecially when the magnitude of the interference picked up by the two loops L1 and L2 are'nearly equal. It is tobe understood that other embodiments of the invention fall clearly within the scope of the present invention and that the scope of the invention is to be limited only by the claims:-

Iclaim:' 7 a 1. In a receiving'system a pairof crossedloops, individual meansfor tuning each loop, a bridge circuit, means for coupling said loops to opposite points of said bridge, a utilizing circuit and means for coupling the input thereof across one arm of the bridge said loops being adapted to'be tuned one above and the other below the desired car- 'rier frequency said' bridge circuit being arranged so as to prevent coupling between the two loops.

2. Ina receiving sysltemya pair of tuned loop antennae each thereof being provided with variable tuning means, a four arm bridge circuit, -'means' for connecting one, of said tuned antennae acrossopposite points of the bridge,rmeans for connecting the other of'said tuned antennae across the other two opposite points of the bridge; said bridge circuit being arranged so as to prevent coupling between the two'loop antennae, saidtwo antennae being arranged substantially atright angles to eachother, a space discharge device provided with input and output circuits. said input circuit including one of the arms of said bridge .circuit, a second'space discharge device provided with a-tunedinput circuit-and an output circuit, said tuned input circuit being provided with a variable tuning element and unicontrol means for varying said last named tuning element and] the, tuning, means. of said loop antennae; simultaneously," said tuning devices being arrangedso that the tunable input circuit is tuned to substantially the desired carrier frequency whereas one of the loop antenna is tuned' slightly above the desired carrier frequency while the other of saidloop antennae is arranged to'be tuned slightly below the desired carrier frequency anda utilizing circuit coupled to the last named output circuit. j

ERICI-I ZEPLERJ- 

